Downhole tools for earth-boring and for other purposes, including rotary drill bits, are commonly used in boreholes or wells in earth formations. Cutting elements used in earth-boring tools often include polycrystalline diamond compact (often referred to as “PDC”) cutting elements, which are cutting elements that include cutting faces of a polycrystalline diamond material. Polycrystalline diamond material is material that includes inter-bonded grains or crystals of diamond material.
Cutting elements may be secured to a body, such as to fixed-cutter earth-boring rotary drill bits (also referred to as “drag bits”). Such fixed-cutter bits typically include a plurality of cutting elements fixedly attached to a bit body of the drill bit, conventionally in pockets formed in blades and other exterior portions of the bit body. Other earth boring tools may include rolling-cone earth-boring drill bits, which include a plurality of roller cones attached to bearing pins on legs depending from a bit body. The roller cones may include cutting elements (sometimes called “inserts”) attached to the roller cones, conventionally in pockets formed in the roller cones.
Brazing is widely used to join cutting elements to such earth-boring tools and components thereof by means of a braze material (e.g., a filler material) that melts upon heating. The braze material coats the surfaces of materials being joined, cooling and solidifying to form a bond. Braze materials typically wet surfaces of the materials being joined and allow the materials to be joined without changing the physical properties of the materials. Braze materials are conventionally selected to melt at a lower temperature than a melting temperature or temperatures of the materials being joined. During a brazing process, heating and cooling of the materials may take place in the open atmosphere, in a controlled atmosphere furnace, or in a vacuum furnace. Braze materials are often alloys based on metals such as Ag, Al, Au, Cu, Ni, Ti, Pd, Pt, Cr, Zr, Sn, Mn, Li, Cd, and alloys thereof. Brazing can be used effectively to join similar or dissimilar materials (e.g., metals to metals, ceramics to ceramics, and metals to ceramics).
Typically, in a brazing process, a filler metal or alloy is heated to a melting temperature above 800° F. (427° C.) and distributed between two or more close-fitting parts by direct placement of the filler material between the parts. In some embodiments, the filler metal or alloy may be drawn into an interface between the parts by capillary action. At the melting temperature of a braze material, molten braze material interacts with the surfaces of the parts, cooling to form a strong, sealed joint. A brazed joint may thus become a sandwich of different layers, and each layer may be metallurgically bonded to one or more adjacent layers.
Brazing cutting elements to an earth-boring tool by conventional methods may cause damage to cutting elements, due to the temperatures required to melt braze material. Furthermore, removal or repositioning of cutting elements brazed to a tool typically requires high temperatures, which can cause further damage to cutting elements or to the tool body.